This invention relates generally to the flow of material, and more particularly to an apparatus for splitting a stream of material into two or more streams.
It is often desirable to split a stream of particulate material into two or more streams each having the same average flow rate. In the mechanical pulping industry, stream splitters are used in order to feed equal amounts of pulp or wood chips into each side of a central rotating disc in one type of refiner. When a stream splitter is used, it is important to feed equal quantities of material in each side of the refiner in order that the refiner operates at its maximum capacity. Furthermore, equal feed in each stream will provide for similar thrust and fiber development on each side of the refiner.
A typical stream splitter for a stream of particulate material has a Y-type divider blade. It is both difficult and expensive to achieve an equal split using this type of device, because in order to get equal flow to each side, the incoming stream either must be 100% full, or perfectly centered, with uniform material density and velocity throughout. Otherwise, the more densely packed or faster side of the "Y" receives more material than the other side.
It is known that a material stream can be accurately split by providing equal opposing discharge openings on a simple screw conveyor. However, in order for equal splitting to result, the following three conditions must be met. First, the screw must rotate fast enough for centrifugal force to keep the material on the barrel of the conveyor, in order to distribute it equally to both outlets. Second, the outlets must be exactly 180.degree. apart. Third, any restriction to flow through the outlets must be the same for each outlet. If material encounters more resistance at one outlet or the other, the material will move to the outlet of least resistance, and the split will not be equal.